The invention relates to thermoplastic elastomers of good dyeability and high strength and elasticity, as well as to high impact-resistant polymer blends produced therefrom, which are suitable for use in the motor vehicle industry, in the domestic appliances industry and in medical technology. The invention also relates to a method for the production of these thermoplastic elastomers.
Thermoplastic elastomers, such as styrene-butadiene block copolymers, thermoplastic polyurethanes, polyester amides, polyether amides, thermoplastic copolyester elastomers and polyolefin alloys with elastomers, are known (Rader, C., Kunststoffe 83 (1993) 10, 777-781, Kunststoffe 86, (1996) 12, 1845-1851).
The special advantage of polyolefin alloys with thermoplastic elastomers lies in that they can be processed easily and recycled advantageously.
The material properties of thermoplastic elastomers based on polyolefin alloys with elastomers, such as the strength and elasticity, are determined by the composition of the polyolefin components and of the elastomeric components and by the distribution of the elastomeric components in the polyolefin component (Moore, P., Polypropylene Handbook, Carl Hanser-Verlag Munich 1996, 218-225).
Known elastomeric components for thermoplastic elastomers based on polypropylene are ethylene-propylene elastomers (EP 672 712; EP 614940), ethylene-propylene-diene elastomers (EP 547 843; EP 409542), ethylene-vinyl acetate copolymers (BE 899507; Coran, A., Rubber Chem. Technol. 54 (1981),892), chlorosulfonated polyethylene (U.S. Pat. No. 4,141,878), elastomeric copolymers of ethylene and C.sub.4 -C.sub.8 olefins, such as elastomeric ethylene-butene copolymers (Kautschuk-Gummi-Kunststoffe 49 (1996) 12, 812-813), ethylene-hexene copolymers or ethylene-octene copolymers (Yu, T., J. Plastic Film & Sheeting 10 (1994) 1,539-564), as well as elastomeric, atactic polypropylenes (EP 334 829) in amounts of 35 to 70% by weight, based on the polyolefin mixture.
Furthermore, the vulcanization of elastomeric components in polyolefin alloys based on polypropylene/ethylene-propylene-diene elastomers, by additives such as dodecyl mercaptan (DE 26 20 820), sulfur (EP 336780) or tetrabutylthiuram disulfide (EP 376 213) is known. However, these formulations have the disadvantage of a strong discoloration, so that semi-finished products and molded objects of these materials can be used only when dyed black.
Thermoplastic elastomers based on polypropylenes and elastomeric C.sub.4 to C.sub.8 olefins have an outstanding dyeability, but a strength level which is significantly lower than that of thermoplastic elastomers based on polypropylenes and vulcanized ethylene-propylene-diene elastomers.
For the formulation of polypropylenes and elastomeric ethylenehexene copolymers, it is known that blends may be modified by electron irradiation (JP 96 301 927).
It is also known that the impact resistance of polypropylenes can be modified by the addition of 10-35% of amorphous ethylene-propylene-diene elastomers (Michaeli, W., Kunststoffberater (1990) 3, 38-43; Kloos, F., Angewandte Makromolekulare Chemie 185/186 (1991), 97-108), ethylene-propylene elastomers (Kim, B., J. Applied Polymer Sci. 60 (1996), 2207-2218, J. Applied Polymer Sci. 60 (1996), 1391-1403), as can reactor blends of polypropylene and ethylene-propylene rubber (Kresge, E., Macromol. Symp. 53 (1992), 173-189, Schwager, H., Kunststoffe 82 (1992) 6, 499-501), ethylene-butene elastomers (Yu, C., SPE-ANTEC '94,2439-2442; SPEANTEC '96, 1995-2000), ethylene-hexene copolymers (Japanese patent 08301 927, Yamaguchi, M., J. Appl. Polymer Sci. 63 (1997), 467-474) and ethylene-octene elastomers (EP 0 769 525, Japanese patent 97 48 920).